Aircraft fuel is typically carried in fuel vessels located within the wings of the aircraft. One typical method for manufacturing aircraft fuel vessels is to manufacture the wing with a sealed, central wing box defined by wing upper and lower surfaces, forward and aft wing spars, inboard and outboard stringers and ribs. These components, typically formed from aluminum, are connected with fasteners, such as rivets. The resulting fuel vessel is then outfitted with multiple access panels that can be opened to (a) allow an operator to seal and/or re-seal the internal joints and (b) allow an inspector to visually inspect the joints for possible corrosion over the life of the aircraft.
One limitation with the foregoing approach is that it is generally not practical for constructing very thin wings, such as the wings typically designed for high-speed (near sonic and supersonic) flight. For example, thin wings require numerous access panels to allow adequate access for sealing and inspection. The additional weight of these access panels is typically prohibitive. Accordingly, thin wings or thin wing portions are generally not suitable for fuel storage.
Another approach for forming airfoil components, such as tails and wing sections, is to bond a metal or fiber reinforced plastic honeycomb core between the airfoil upper and lower surfaces, in place of the foregoing spars, ribs and stringers. The entire assembly is then cured in an autoclave to form a monolithic structure. One drawback with this approach, however, is that the core is not suitable for fuel storage because the cell openings of the core (oriented normal to the airfoil upper and lower surfaces) run transverse to the desired fuel flow direction, which is from outboard to inboard.